Vein filter

ABSTRACT

A vessel filter movable between a collapsed position for delivery to the vessel and an expanded position for placement within the vessel, and having a filter portion having a converging region to direct particles toward the center. The filter portion converges into a tubular portion. The second region is flared in the expanded position to have a transverse dimension increasing in a direction away from the filter portion and includes a vessel engaging portion. The first region has a spacer to keep the filter more toward a center of a vessel, wherein in the collapsed position the spacer extends axially in an elongated position cranially of the cranial end of the filter and in the expanded position the spacer forms a looped region extending radially with respect to a longitudinal axis of the filter. The spacer has a first end attached to the internal surface of the tubular portion and extends within the tubular portion and emerges cranially from the tubular region to form the looped region.

This application claims priority from provisional application Ser. No.61/953,829, filed Mar. 15, 2014 and is a continuation in part ofapplication Ser. No. 13/935,954, filed Jul. 5, 2013 which is acontinuation of application Ser. No. 12/551,605, filed Sep. 1, 2009, nowU.S. Pat. No. 8,500,774 which claims priority from provisionalapplication Ser. No. 61/191,903, filed Sep. 12, 2008 and is acontinuation-in-part of application Ser. No. 11/888,929, filed Aug. 3,2007, now U.S. Pat. No. 8,062,326, which claims priority fromprovisional application Ser. No. 60/840,888, filed Aug. 29, 2006. Theentire contents of each of these applications are incorporated herein byreference.

BACKGROUND

Technical Field

This application relates to a vascular filter and more particularly to avein filter for capturing blood clots within the vessel.

Background of Related Art

Passage of blood clots to the lungs is known as pulmonary embolism.These clots typically originate in the veins of the lower limbs and canmigrate through the vascular system to the lungs where they can obstructblood flow and therefore interfere with oxygenation of the blood.Pulmonary embolisms can also cause shock and even death.

In some instances, blood thinning medication, e.g. anticoagulants suchas Heparin, or sodium warfarin can be given to the patient. Thesemedications, however, have limited use since they may not be able to beadministered to patients after surgery or stroke or given to patientswith high risk of internal bleeding. Also, this medication approach isnot always effective in preventing recurring blood clots.

Therefore, surgical methods to reduce the likelihood of such pulmonaryembolisms by actually blocking the blood clot from reaching the lungshave been developed. To this end, minimally invasive surgical techniqueshave been developed involving the placement of a mechanical barrier inthe inferior vena cava. These barriers are in the form of filters andare typically inserted through either the femoral vein in the patient'sleg or the right jugular vein in the patient's neck or arm under localanesthesia. The filters are then advanced intravascularly to theinferior vena cava where they are expanded to block migration of theblood clots from the lower portion of the body to the heart and lungs.

These prior filters take various forms. One type of filter is composedof coiled wires such as disclosed in U.S. Pat. Nos. 5,893,869 and6,059,825. Another type of filter consists of legs with free ends havinganchors for embedding in the vessel wall to hold the filter. Thesefilters are disclosed, for example, in U.S. Pat. Nos. 4,688,553,4,781,173, 4,832,055, and 5,059,205, 5,984,947 and 6,007,558. Anothertype of filter is disclosed in U.S. Pat. No. 6,214,025 consisting ofwires twisted together to form a cylindrical anchoring portionconforming to the inner vessel wall surface to exert a radial force anda conical filtering portion.

Several factors have to be considered in designing vein filters. Onefactor is that the filter needs to be securely anchored within thevessel wall, while avoiding traumatic engagement and damage to the wallas well as damage to the neighboring abdominal aorta. Another factor isthat the filter must be collapsible to a sufficiently small size to beeasily maneuvered and atraumatically advanced intravascularly to theinferior vena cava or other target vessel. Thirdly, the filter shoulddirect the blood clots to the center of the vessel to improvedissolution of the clot within the vessel by the blood flow.

The filters disclosed in the commonly assigned co-pending U.S. Pat. No.7,704,266 (hereinafter “the '266 patent”) and U.S. Pat. No. 8,162,972(hereinafter the '972 patent), the entire contents of both of which areincorporated herein by reference, satisfy the foregoing parameters. Thefilters have sufficient anchoring force to retain the filter within thevessel while providing atraumatic contact with the vessel wall, have aminimized insertion (collapsed) profile to facilitate delivery throughthe vascular system to the surgical site, and direct migration of thecaptured blood clots to the center of the vessel. The filters alsoprovide simplified insertion through the femoral or the right jugularvein or arm into the inferior vena cava.

The filters of the '266 and '972 patents can advantageously be readilyremoved minimally invasively, e.g. intravascularly, from the patient,thus advantageously providing for a temporary filter. Thus, thesefilters advantageously strike the balance of having structure to providesufficient anchoring while enabling atraumatic removal from the vesselafter a period of time. Certain filters of the '266 and '972 patentsalso advantageously have a retrieval end configured to facilitategrasping by a snare as well as to facilitate withdrawal by providing asmooth transition into a retrieval sheath.

The filters of the '429 are very effective in achieving their desiredfunctions, whether used as a permanent or temporary filter. The presentapplication provides a modification to the filters to further improvecentering of the filter in the vessel to further facilitate removal ifused as a temporary filter.

SUMMARY

The present invention provides in one aspect a vessel filter comprisinga first region and a second region, the filter movable between acollapsed position for delivery to the vessel and an expanded positionfor placement within the vessel. The first region has a filter portionhaving a converging region to direct particles toward the center of thefilter, the filter portion converging into a tubular portion, and thetubular portion having an internal surface. The filter terminates at acranial end. The second region is flared in the expanded position tohave a transverse dimension increasing in a direction away from thefilter portion toward a caudal end, and includes a vessel engagingportion. The first region has a spacer to keep the filter more toward acenter of a vessel upon placement of the filter within the vessel,wherein in the collapsed position of the filter the spacer extendsaxially in an elongated position cranially of the cranial end of thefilter and in the expanded position of the filter the spacer forms alooped region extending radially with respect to a longitudinal axis ofthe filter. The spacer has a first end attached to the internal surfaceof the tubular portion and extending within the tubular portion andemerges cranially from the tubular region to form the looped region.

In some embodiments, the first region includes a plurality of spacedapart elongated struts and a plurality of connecting struts extending atan angle from the elongated struts. In some embodiments, the loopedregion extends beyond a cranial edge of the tubular portion in theexpanded position of the filter; in other embodiments, the looped regionencircles the tubular portion of the filter in the expanded position ofthe filter.

In some embodiments, the tubular portion includes a retrieval structurefor removal of the filter. In some embodiments, the spacer has a cranialend terminating in a retrieval structure for removal of the filter.

The filter can be formed from a laser cut tube and composed of shapememory material.

The vessel retrieving structure can include a hook.

In some embodiments, the looped region has a transverse dimension whichdoes not exceed a transverse dimension of a caudal end of the filter inthe expanded configuration.

In accordance with another aspect, the present invention provides avessel filter comprising a first region and a second region, the filtermovable between a collapsed position for delivery to the vessel and anexpanded position for placement within the vessel. The first region hasa filter portion having a converging region to direct particles towardthe center of the filter, the filter portion converging into a tubularportion, and the tubular portion having an internal surface. The filterterminates at a cranial end. The second region is flared in the expandedposition to have a transverse dimension increasing in a direction awayfrom the filter portion toward a caudal end, the second region includinga vessel engaging portion. The first region has a spacer to keep thefilter more toward a center of a vessel upon placement of the filterwithin the vessel, the spacer having a plurality of arms, wherein in thecollapsed position of the filter at least a portion of the plurality ofarms extend caudally within the tubular portion and in the expandedposition of the filter the plurality of arms curve toward a cranial endof the filter.

In some embodiments, the vessel filter includes interconnecting strutsin a filtering region of the body to form closed geometric shapes, andin the expanded position of the filter, the plurality of arms extendthrough the closed geometric shapes. In some embodiments, the spacer inthe expanded position has a transverse dimension less than a transversedimension of the caudal end of the filter in an expanded position.

In some embodiments, the spacer is attached to the internal surface ofthe tubular portion.

In accordance with another aspect, the present invention provides avessel filter comprising a first region and a second region, the filtermovable between a collapsed position for delivery to the vessel and anexpanded position for placement within the vessel. The first region hasa filter portion having a converging region to direct particles towardthe center of the filter, the filter portion converging into a tubularportion, and the tubular portion having an internal surface. The filterterminates at a cranial end. The second region is flared in the expandedposition to have a transverse dimension increasing in a direction awayfrom the filter portion, the second region including a vessel engagingportion. The first region has a spacer to keep the filter more toward acenter of a vessel upon placement of the filter within the vessel. Thespacer includes a tubular region and a plurality of arms extending fromthe tubular region, wherein in the collapsed position of the filter theplurality of arms extend axially toward the caudal end of the filter andoverlie an external surface of the tubular portion of the filter, and inthe expanded position of the filter the plurality of arms have tipspointing toward the caudal end of the filter.

In some embodiments, the arms extend substantially perpendicular to thetubular portion and then bend toward the caudal end.

In some embodiments, the filter has retrieval structure at the cranialend for filter removal and the tubular region of the spacer has aterminal end, the terminal end positioned caudally of the retrievalstructure of the filter. In some embodiments, the spacer includesretrieval structure for removal of the filter, the retrieval structureextending cranially of the tubular portion of the filter.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiment(s) of the present disclosure are described hereinwith reference to the drawings wherein:

FIG. 1 is a perspective view of a first embodiment of the vein filter ofthe present invention in the collapsed (retracted) configuration, andshown removed from a delivery tube/sheath;

FIG. 2 is an enlarged broken side view of a portion of the vein filterof FIG. 1;

FIG. 3 is a developed view of the retention hooks of the vein filter ofFIG. 1;

FIG. 4A is a perspective view of the vein filter of FIG. 1 in anexpanded (radially extending) configuration;

FIG. 4B is a side view of the vein filter of FIG. 4A;

FIG. 5 is a front view of the vein filter of FIG. 4A;

FIG. 6 is a side view of the vein filter of FIG. 1 with the struts inthe expanded configuration and the spacers in the collapsedconfiguration;

FIG. 7 is a close up perspective view of the detail of FIG. 6;

FIG. 8 is a perspective view of a cranial end of a filter of the '266patent showing the retrieval hook of the filter;

FIG. 9 is a view similar to FIG. 8 except showing the cranial end of thefilter of FIG. 1, the spacers shown in the collapsed position;

FIG. 9A is a perspective view of an alternate embodiment of theretrieval portion of the filter having an extended hook;

FIG. 10 is a view similar to FIG. 9, except showing a broken view of thespacers extending radially from the tubular portion;

FIG. 11 is a perspective view of an alternate embodiment of the veinfilter of the present invention having a single spacer loop, the filterand spacer shown in the expanded configuration;

FIG. 12 is a front view of the filter of FIG. 11;

FIGS. 13, 14, and 15 illustrate delivery and placement of the vesselfilter of FIG. 1 in the inferior vena cava wherein FIG. 13 illustratesinitial insertion of the delivery sheath through the femoral vein, FIG.14 illustrates the delivery sheath being advanced toward the inferiorvena cava just below (upstream) the juncture of the renal arteries; andFIG. 15 illustrates the filter in the expanded placement configurationin the inferior vena cava;

FIG. 15A illustrates an initial step in removal of the filter from theinferior vena cava by a retrieval snare and catheter;

FIG. 16 is a side view of an alternate embodiment of the filter of thepresent invention having spacers at different angles to the longitudinalaxis of the filter, the spacers shown in the expanded position;

FIG. 17 is a perspective view of an alternate embodiment of the filterof the present invention having a single spacer extending in a singleplane, the spacers shown in the expanded position;

FIG. 17A is a close up view of the area of detail of FIG. 17;

FIG. 18 is a perspective view of another alternate embodiment of thefilter of the present invention having a single spacer extending inmultiple planes;

FIG. 19 is a perspective view of the cranial end of another alternateembodiment of the filter of the present invention having two spacers,the spacers shown in the expanded position;

FIG. 19A is a view similar to FIG. 19 except showing the spacers in thecollapsed position;

FIG. 20 is a perspective view of the cranial end of yet anotheralternate embodiment of the filter of the present invention having twospacers, the spacers shown in the expanded position;

FIG. 20A is a view similar to FIG. 20 except showing the spacers in thecollapsed position;

FIG. 21 is a perspective view of the cranial end of another alternateembodiment of the filter of the present invention showing the twospacers in the expanded position;

FIGS. 22A-22C illustrate another alternate embodiment of the cranial endof the filter of the present invention wherein FIG. 22A is a perspectiveview of the cranial end in the collapsed configuration, FIG. 22B is aside view in the collapsed configuration and FIG. 22C is a perspectiveview in the expanded configuration;

FIG. 23 is a perspective view of an alternate embodiment of the veinfilter of the present invention in the collapsed (retracted)configuration, and shown removed from a delivery tube/sheath;

FIG. 24 is a perspective view of the cranial end of the filter of FIG.23 shown within a delivery sheath;

FIG. 24A is a view similar to FIG. 24 showing partial deployment of thefilter from the delivery sheath;

FIG. 25 is a perspective view of the vein filter of FIG. 23 in theexpanded configuration;

FIG. 25A is an enlarged view of a region of the filter of FIG. 25;

FIG. 26A is a perspective view of another alternate embodiment of thevein filter of the present invention shown in the collapsedconfiguration;

FIG. 26B is a perspective view of the filter of FIG. 26A in the expandedconfiguration;

FIG. 26C is a side view of the cranial end of the filter of FIG. 26B;

FIG. 26D is an enlarged perspective view of the cranial end of thefilter of FIG. 26B;

FIG. 26E is an enlarged perspective view of the cranial end of analternate embodiment of the filter of the present invention;

FIG. 27A is a perspective view of an alternate embodiment of the veinfilter of the present invention in the collapsed configuration;

FIG. 27B is a perspective view of the filter of FIG. 27B in the expandedconfiguration;

FIG. 28A is a perspective view of another alternate embodiment of thevein filter of the present invention in the collapsed configuration;

FIG. 28B is a perspective view of the filter of FIG. 28A in the expandedconfiguration;

FIG. 28C is a close up perspective view of a cranial portion of thefilter of FIG. 28A in the collapsed configuration;

FIG. 28D is a close up perspective view of the cranial portion of thefilter of FIG. 28B in the expanded configuration;

FIG. 28E is a perspective view of the cranial end of an alternateembodiment of the filter of the present invention;

FIG. 29A is a perspective view of another alternate embodiment of thevein filter of the present invention in the collapsed configuration;

FIG. 29B is a perspective view of the filter of FIG. 29A in the expandedconfiguration;

FIG. 29C is a perspective view of another alternate embodiment of thevein filter of the present invention in the expanded configuration; and

FIG. 29D is a perspective view of another alternate embodiment of thevein filter of the present invention in the expanded configuration.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawings, wherein like reference numerals identifysimilar or like components throughout the several views, the veinfilters of the present invention are described for placement within theinferior vena cava to capture blood clots or other particles which couldotherwise pass to the lungs.

The filter is movable from a low profile collapsed configuration tofacilitate insertion through the delivery sheath to a larger expandedplacement configuration to enable atraumatic engagement with the vesselwalls to secure (mount) the filter within the inferior vena cava. Thefilter is preferably substantially bell-shaped and preferably has aflared or mounting region (portion/section) and a filtering region(portion/section). The filtering region has inwardly directed struts,terminating in a converging region, thereby directing particles towardthe central axis of the filter. By directing the particles to thecenter, they will be exposed to greater blood flow (since there isgreater flow at the center than near the wall of the vessel) whichimproves dissolution of the particles. The filter increases intransverse dimension to form a flared region. The flare provides lesscontact area than a straight region, resulting in less tissue ingrowthto facilitate removal of the filter if desired. The flare also reducesthe chance of vessel distortion if inserted into a curved vena cava. Thefilter also has one or more spacers to space the cranial end of thefilter from the vessel wall to facilitate removal.

Turning now to details of the filter of the present invention and withinitial reference to FIGS. 1 and 2, the filter is designated generallyby reference numeral 10 and is shown in a collapsed configuration fordelivery. Filter 10 is preferably formed from a single tube 11. In apreferred embodiment, the filter tube 11 is composed of shape memorymaterial, such as Nitinol, a nickel titanium alloy, or elgiloy, however,other materials such as stainless steel are also contemplated. Aplurality of cutouts are formed in the filter 10, preferably by lasercutting although other techniques are contemplated. In the illustratedembodiment, six elongated cutouts are formed, creating six strips orstruts 14 of substantially uniform width separated by the cutouts.

The collapsed configuration of filter 10 reduces the overall profile tofacilitate delivery to the site. The diameter or transverse dimension offilter 10 in the collapsed configuration is preferably about 2 mm andmore preferably about 1.7 mm. Other dimensions are also contemplated.The filter is thus preferably dimensioned for insertion through a 6French delivery system and through a 6 French catheter. The diameter ortransverse dimensions of the filter in the expanded placementconfigurations (e.g. FIGS. 4A and 4B) is greater than the diameter ortransverse dimension in the collapsed (delivery) configuration of FIG.1.

FIGS. 4-5 illustrate the expanded placement configuration of the filter10. FIGS. 6 and 7 illustrate the expanded configuration of the strutswith the spacers in the collapsed position (not exposed from the sheath)to help illustrate the invention, a configuration that would occurbriefly in certain insertion directions of the filter. Filter 10 isgenerally bell-shaped in configuration. Filter 10 has a flared region 17and a converging region 21 at the filtering section 19. The transversedimension of the filter at the flared (or mounting/anchoring) region 17is greater than the transverse dimension at filtering section 19.Diameters (or transverse dimensions) preferably range from about 18 mmto about 32 mm, depending on the internal diameter of the vessel wall aswill be explained in more detail below. Other dimensions are alsocontemplated. The elongated struts 14 are spaced apart as shown andextend at an angle away from the longitudinal axis L of filter 10 inregion 17 to provide a flare. Preferably, this angle or taper is about8°, although other dimensions are contemplated. When expanded, the sixstruts 14, as shown, are preferably spaced approximately 60 degreesapart. It is also contemplated that a fewer or greater number of strutsand spacing other than 60 degrees be provided.

Filtering section 19 extends from the flared region 17, and extendstoward the central longitudinal axis L of the filter 10 and convergesinto tubular portion 18 at the cranial end of the filter.

The struts 14 of filter 10 terminate in hooks 72 a, 72 b which extendsubstantially perpendicular from the strut, achieved by torquing thestruts at the region 85 so the hooks bend out of the plane. A first setof hooks 72 a is larger than a second set of hooks 72 b. Preferably whenformed in a laser cut tube, hooks 72 a are formed so that they occupy aregion equivalent to the transverse dimension of two adjacent struts.Smaller hooks 72 b are spaced axially with respect to each other andaxially inwardly with respect to larger hooks 72 a as in the filterhooks of the '266 patent to minimize the collapsed profile (transversedimension) of the filter when collapsed for insertion. The penetratingtips 76 a, 76 b of hooks 72 a, 72 b, respectively, penetrate the tissueto retain the filter, preferably temporarily, and point distally, towardthe cranial (or distal) end of the filter.

Each of the hooks 72 a, 72 b has a series of teeth 79 a, 79 b,respectively to engage the vessel wall to provide additional retentionto prevent movement of the filter in the caudal direction. In apreferred embodiment, the larger hooks 72 a have four teeth and thesmaller hooks 72 b have three teeth, although a different number ofteeth could be provided. A heel 77 a, 77 b, is provided which extendspast (proximally or caudal of) the respective hook 72 a, 72 b tofunction as a stop to prevent the filter strut portions from goingthrough the vessel wall. The angle of the heel 77 b in the smaller hooks72 b is less than the angle in the larger hooks 72 a to provide room fornesting of the hooks as shown in FIG. 3. For clarity, not all of thehooks are fully labeled. Note this hook configuration with the teethand/or heel can be utilized with the filters of the '429 application.

The six filter struts or strut portions 14 curve outwardly from tubularportion 18, extend radially therefrom and divide into two connectingfilter struts or strut portions 14 a, 14 b (preferably of equal width,although differing dimensions are contemplated) that angle way from eachother (in different directions) to extend to the connecting strutportion of an adjacent strut 14. Thus, connecting strut portion 14 a ofone strut 14 interconnects with the connecting strut portion 14 b of anadjacent strut at joining region 14 d. This forms closed geometricshapes 25, preferably substantially diamond shaped in configuration. Forclarity, not all of the identical parts are labeled in the drawing.

In the illustrated embodiment, preferably six struts are providedforming twelve interconnecting struts, however a different number ofstruts and closed geometric shapes can be provided. Note that althoughall six struts 14 are shown interconnected, it is also contemplated thatfewer than all the struts can be interconnected. Also, the strut widthcan vary as described with respect to the filters disclosed in the '429application.

After convergence of strut portions 14 a, 14 b at joining region 14 d,it transitions into elongated mounting strut portions 14 c which formflared mounting or anchoring region 17. The length of the strut portions14 c in the anchoring region 19 can vary, with increased/decreasedlength increasing the flexibility/rigidity of the struts. The thicknessof the strut portions can also vary to affect flexibility/rigidity.

As in the other embodiments described in the '266 and '972 patents,terms such as interconnected, joined, etc., are used for ease ofdescription, it being understood that preferably these portions areintegral as they are preferably formed from a single tube. Also,mounting struts and filter struts used to describe the variousembodiments disclosed herein can be considered as mounting strut“portions” or “sections” and filter strut “portions” or “sections” ofthe same struts if the filter is formed integrally, e.g. from a cuttube.

The tubular portion 18 is preferably in the form of a retrieval hook 92as described with respect to the embodiment of FIG. 20 in the '266patent. Other retrieval structure can also be utilized. Hook 92 isdescribed in more detail below.

Two spiral cuts 45 a, 45 b are formed in the tube during manufacture,preferably by laser cutting, to enable two strips to be formed creatingfirst and second spacers 40 a, 40 b for the filter. In the collapsedposition, spacers 40 a, 40 b are in a substantially aligned positionwith respect to tubular portion 18, i.e. substantially flush with thetubular portion 18. Spacers 40 a, 40 b are maintained in this collapsedposition during delivery to the surgical site. (See e.g. FIG. 1). Thespacers 40 a, 40 b have a shape memorized position forming loops asshown in FIG. 4A. Thus, once exposed from the delivery sheath, thespacers 40 a, 40 b move from their collapsed position to their shapememory looped position of FIGS. 4A, 4B and 5. The surface 42 a, 42 b ofthe loop of each spacer 40 a, 40 b engages opposite sides (lyingapproximately 180° apart) of the vessel wall to maintain centering ofthe cranial end of the filter and to space tubular portion 18 andretrieval hook 92 away from the vessel wall. This spacing preventstissue ingrowth around the hook, thereby making it easier to grasp andremove filter 10.

The loops of spacers 40 a, 40 b are open, somewhat oval shaped loops,terminate in ends 44 a, 44 b and lie in substantially alternate spiralplanes. The first strip cut into tubular portion 18 unravels from aproximal end 48 a of cutout 45 a to a distal end 46 a of cutout 45 a toform spiral spacer 40 a (see e.g. FIGS. 4B and 7). The second strip cutinto tubular portion 18 unravels from a proximal end 48 b of cutout 45 bto a distal end 46 b of cutout 45 b to form spiral spacer 40 b. In theFIG. 4 embodiment, the spacer loops 40 a, 40 b lie in planes that aresubstantially perpendicular to the longitudinal axis L of the tubularportion 18 and filter 10. However, alternatively the spacer loops couldlie in planes at angles other than 90 degrees and could lie in planesnot parallel to each other. Examples of different angles of spacer loopswith respect to the longitudinal axis of the tubular portion of thefilter are shown by way of example in FIG. 16. Two angled spacer loops(e.g. about 75 degrees) are designated by reference numeral 70′ andsmaller acute angled spacer loops, (e.g. about 45 degrees) aredesignated in phantom by reference numeral loop 70″. The othercomponents of the filter are identical to filter 10 and are designatedwith corresponding prime (′) reference numerals.

A comparison of FIGS. 8-10 illustrates that in the preferred embodiment,the length of tubular portion 18 remains substantially unchanged oncethe filter is implanted, even with the addition of the spacers. FIG. 8illustrates a cranial end of a filter of the '266 patent showing theretrieval hook H of the filter. The tubular portion P has a length L1preferably ranging from about 0.100 inches to about 0.600 inches, andpreferably about 0.300 inches. The tubular portion 18 of FIG. 9, whichis the embodiment of FIG. 1, has a length L2, preferably ranging fromabout 0.500 inches to about 1.700 inches, and preferably about 0.881inches which is greater than length L1 due to the space needed to createthe spiral spacers 40 a, 40 b. However, once the spacers 40 a, 40 b movefrom their aligned position to their expanded position, the end of thetubular portion 18 contracts to close the gap created by the spiralcutouts to move to a length L3 which is preferably closed to length L1.

FIGS. 11 and 12 illustrate an alternate embodiment of the filter,designated by reference numeral 110. Filter 110 is identical to filter10, except for the tubular portion and spacer, and therefore has beenlabeled with numerals in the “100” series corresponding to the doubledigit numbering of filter 10. Thus, filter 110 has struts 114,interconnecting struts 114 a, 114 b, hooks 172 a, 172 b, etc. andtherefore for brevity these parts will not again be described.

Tubular portion 150 of filter 110 has a hook 192 identical to hook 92 ofFIG. 1. However, tubular portion 150 has a single spiral cutout 152,preferably formed by laser cutting, which forms a spiral spacer 154. Thespiral spacer 154 has a shape memory position of that shown in FIGS. 11and 12, extending radially from the tubular portion 150. When exposedfrom the sheath it unravels to move from a collapsed positionsubstantially flush with the tubular portion 150 to its shape memoryposition forming an open loop starting at end 155 and wrapping over 360degrees, terminating at edge 157. In this manner loop portions 156 and158 are 180 degrees apart and the circular loop surfaces contact theinner wall of the vessel. It is also contemplated that the spacer canwrap a smaller or greater distance (degrees) than that shown and be ovalor shapes other than circular. The loop can lie in a single plane or inmultiple planes.

FIG. 17 discloses an alternate embodiment of the filter which isidentical to the filter shown in FIG. 11 except for the spiral spacer264. The filter 210 is labeled with reference numerals in the “200series” corresponding to the “100 series” labeled parts of the FIG. 11embodiment and therefore has struts 214, hooks 272 a, 272 b, etc. Thetubular portion and spacer, being different, have non-correlatingreference numerals. More specifically, tubular portion 260 has a spiralcutout 262 to form a spacer 264. The cranial terminal end 266 of thecutout 262 has an increased width to form a spacer end 269 of increasedwidth “w”, shown in FIG. 17A. This provides increased support for thespacer as it reduces stress at that part. Spiral spacer 264 loops aroundtubular portion 260 in a similar manner as spacer 154 of FIG. 11,preferably wrapping over 360 degrees, although other degrees arecontemplated. Opposed looped ends 267 and 269 are about 180° apart andthe outer surfaces contact opposing sides of the vessel wall. As withspacers 254, the outer surfaces along the loop contact the vessel walldue to the circular configuration of the spacer 264.

In the embodiment of FIG. 18, the spacer 364 of filter 310 wraps aroundthe tubular portion 360 in different planes, as opposed to the singleplane of the embodiment of FIGS. 11 and 17. More specifically, in theexpanded position, spacer 364 emerges from the cranial end 366 of cutout365 and wraps at an angle toward the caudal end of the filter. Thus, asseen, the first end 372 of loop portion 370 lies in a plane proximal ofthe plane containing end 371 of loop portion 370 and distal of the planecontaining the end 374 of loop portion 376. In other words, loop portion378 lies, as viewed axially, between loops 370, 376. The remainingportions of the filter are identical to filter 210 of FIG. 17 and arelabeled with corresponding parts in the “300” series.

FIGS. 19 and 19A illustrate the cranial end of an alternate embodimentof the filter having two looped spacers extending radially from thetubular portion 324. In the collapsed position of FIG. 19A, spacers 320,322 are wrapped around tubular portion 324 so they are substantiallyflush with the wall of the tubular portion 324. The spacers 320, 322 areformed by two spiral cutouts 326, 328 formed in the wall of tubularportion 324. In the expanded position, spacer 320 emerges from theproximal (caudal) end 329 of cutout 328, extending in a substantiallycircular or spiral path around the tubular portion 324, preferably forabout 300 degrees (although other degrees are contemplated), withsurfaces 321, 323 about 180° apart contacting opposing surfaces of thevessel wall. Spacer loop 320 terminates at end 323 to form an open loop.Spacer 322 emerges from the distal (cranial) end of the cutout 326,wrapping around tubular portion 324 in the direction opposite of spacer320. Similar to spacer 320, spacer 322 extends for about 300 degrees(although other degrees are contemplated), with opposing surfaces 325,327 contacting opposite portions of the vessel wall. Spacer loop 322terminates at end 331 to form an open loop. Hook 330 is preferablyidentical to hook 92 of the filter embodiment of FIG. 1.

In the embodiment of FIG. 20, open spacer loops 420 and 422 each startat a proximal end of cutout 426, with spacer 420 starting proximal ofspacer 422. Cutout 426 has first cutout 426 a and second cutout 426 b,formed in an alternating pattern. Spacers 420, 422 lie in multipleplanes, preferably wrap around tubular portion 424 in oppositedirections, extending for about 300 degrees (although other degrees arecontemplated) and have respective opposing surfaces 421, 423 and 425,427, respectively for contacting opposing sides of the vessel wall.Spacers 420, 422 terminate in ends 430, 432.

In the embodiment of FIG. 21, open spacer loops 520, 522 are formedemerging from the distal end of cutouts 526 a, 526 b, with spacer 520emerging distal of spacer 522. Spacers 520, 522 lie in different planes.Similar to loops 420, 422 of the embodiment of FIG. 21, spacer 520 hasopposing surfaces 521 and 523 and spacer 522 has opposing surfaces 525,527. Loops 520, 522 lie in multiple planes.

In the embodiment of FIG. 22, open spacer loops 620, 622 extend from thedistal end of cutout 626 a, 626 b. As shown, the cutouts are formed inan intertwined spiral fashion resulting in a spiral spacer whenunraveled (expanded). The solid strip between cutout 626 a is designatedby reference numeral 630 and the solid strip between cutout 626 b isdesignated by reference numeral 632.

FIGS. 23-25 illustrate an alternate embodiment of the filter. Filter 710is identical to filter 10, except for the tubular portion at the cranialend and the spacer, and therefore has been labeled with numerals in the“700” series corresponding to the double digit numbering of filter 10.Thus, filter 710 has struts 714, interconnecting struts 714 a, 714 b,struts 714 c in the mounting region terminating in hooks 772 a, 772 b,closed cells 725, etc. and therefore for brevity these parts will notagain be described.

Tubular region 801 has cutout 803 extending from proximal cutout end 805to opening 807 in the tubular region 801. Spacer 810 extends from thecutout end 805 upwardly from the tubular region 801, with a curvedtransition 811, and then (as viewed in FIGS. 25 and 25A) wraps under thetubular region 801 and encircles the tubular region as it forms a loop812. Preferably the loop 812 is an open loop such that in the expandedposition it wraps around in a loop less than 360 degrees, althoughwrapping to other degrees, including 360 degrees or more, is alsocontemplated. Preferably the loop 812 in the expanded configuration issubstantially perpendicular to a longitudinal axis of the filter, i.e.an axis parallel to a longitudinal axis of the filter passes through theopening 814.

In the delivery position, as shown in FIGS. 24 and 24A, the spacer 810is elongated, extending distally from the tubular region 801 andpreferably along an axis substantially parallel to a longitudinal axisof the filter 700 and tubular region 801. When the filter is exposedfrom the delivery sheath D, the spacer 810 forms the looped shape asshown in FIG. 25. As with the other filters described herein, filter 800is preferably made of shape memory material and formed by laser cuttinga shape memory tube. However, other materials are also contemplated.

In one method of manufacturing the filter 800, two filters with spacers810 are formed from a section of shape memory tube. That is, the samesection of tube can be used to from a spacer for one filter and spacerfor a second filter. More specifically, a tube would be laser cut sothat a first filter is formed in the direction of FIG. 23, so the spacerextends to the left as viewed in the Figure, and the second filter isformed in the opposite direction so the spacer would extend to the rightas viewed in FIG. 23. In this manner, the spacers are formed adjacentone another from the same section of tube.

The filter can be inserted through the jugular vein in the neck of thepatient or through the femoral vein in the leg of the patient or thearm. The filters can also be placed in the superior vena cava.

FIGS. 26A-26D illustrate an alternate embodiment of the filter,designated generally by reference numeral 1010, and having a spacer1040. Filter 1010, similar to filter 10 of the embodiment of FIG. 1, ispreferably formed from a single tube, and is preferably composed ofshape memory material such as Nitinol. A plurality of cutouts are formedin the filter 1010, preferably by laser cutting, although othertechniques are contemplated, to thereby form struts 1014.

Filter 1010, as shown in the expanded configuration of FIG. 26B, has afilter portion or section 1020 and a mounting portion or section 1030.As shown, filter 1010, like filter 10, is generally bell-shaped inconfiguration. Filter 1010 has a flared region and at the opposite end aconverging region 1021 at the filtering section 1020. The transversedimension of the filter at the flared (or mounting/anchoring) region1030 is greater than the transverse dimension at filtering section 1020.Elongated struts 1014 are spaced apart as shown and extend at an angleaway from the longitudinal axis of the filer 1010 to provide a flare.

The struts 1014 of filter 1010 terminate in hooks 1072 a, 1072 b similarto hooks 72 a, 72 b of FIG. 1. The first set of hooks 1072 a can belarger than the second set of hooks 1072 b, as discussed above.Alternatively, in this embodiment, as well as in the other embodiments,the hooks 1072, 1072 b can be the same size. The penetrating tips 1076a, 1076 b of hooks 1072 a, 1072 b, respectively, penetrate the tissue toretain the filter, preferably temporarily, and point toward the cranialend of the filter.

The six filter struts or strut portions 1014 extend longitudinally andthen curve outwardly from tubular portion 1018, extend radiallytherefrom and divide into two connecting filter struts or strut portions1014 a, 1014 b (preferably of equal width, although differing dimensionsare contemplated) that angle way from each other (in differentdirections) to extend to the connecting strut portion of an adjacentstrut 1014. Thus, connecting strut portion 1014 a of one strut 1014interconnects with the connecting strut portion 1014 b of an adjacentstrut at joining region 1014 d. This forms closed geometric shapes 1025,preferably substantially diamond shaped in configuration although othershapes are contemplated. For clarity, not all of the identical parts arelabeled in the drawings.

In the illustrated embodiment, preferably six struts 1014 are providedforming twelve interconnecting struts, however a different number ofstruts and closed geometric shapes can be provided. Note that althoughall six struts 1014 are shown interconnected, it is also contemplatedthat fewer than all the struts can be interconnected. Also, the strutwidth can vary as described with respect to the filters disclosed in the'266 patent.

After convergence of strut portions 1014 a, 1014 b at joining region1014 d, it transitions into elongated mounting strut portions 1014 cwhich form the flared mounting or anchoring region 1030. The length ofthe strut portions 1014 c in the anchoring region 1030 can vary, withincreased/decreased length increasing the flexibility/rigidity of thestruts. The thickness of the strut portions can also vary to affectflexibility/rigidity.

As in the other embodiments described in the '266 patent, terms such asinterconnected, joined, etc., are used for ease of description, it beingunderstood that preferably these portions are integral as they arepreferably formed from a single tube. Also, mounting struts and filterstruts used to describe the various embodiments disclosed herein can beconsidered as mounting strut “portions” or “sections” and filter strut“portions” or “sections” of the same struts if the filter is formedintegrally, e.g., from a cut tube.

The tubular portion 1018 preferably includes a retrieval hook 1092 asdescribed with respect to the embodiment of FIG. 7 described herein(hook 92) and FIG. 20 in the '266 patent. Other retrieval structure canalso be utilized.

Spacer 1040 is formed from a wire 1042, preferably a round wire, whichis attached to the filter. Wire 1042 has a first cranial end 1042 a anda second caudal end 1042 b. Second end 1042 b is attached to an innersurface 1018 a of tubular portion 1018, preferably by laser welding orcrimping, although other methods of attachment are contemplated. Wire1042 extends within tubular portion 1018 and extends cranially beyondthe retrieval hook 1092, i.e., exiting cranially of the tubular portion1018. Wire 1042 then loops in a lasso like or halo like manner. Asshown, in the expanded configuration of FIGS. 26B and 26D, wire 1042 hasa loop 1044, extending preferably about 360 degrees, althoughalternatively it could extend less than 360 degrees or alternativelyextend more than 360 degrees so it overlaps a region of the loop. Asshown, the elongated portion 1045 of wire 1042 is attached to the innerwall of tubular portion 1018, extends to expanded cranial end 1042 a,curves at region 1047 to extend back toward the caudal end at region1046 and then curves at region 1048 to form the loop 1044. The loop 1044terminates in free end 1044 a. The loop 1044 as shown encircles aportion of the tubular region 1018, e.g., adjacent the hook 1092 (seeFIG. 26C). However, it is also contemplated that the elongated portion1045 can be of sufficient length so that the loop 1044 is spacedcranially from the cranialmost edge 1092 a of the hook 1092 so it isdoes not surround, i.e., overlap, the hook 1092 or tubular region 118.As can be appreciated, in the expanded position, the loop 1044 functionsto better center the filter during placement by keeping the cranial endof the filter away from the vessel wall during placement to limit tissueingrowth around the hook 1092 and facilitate subsequent removal.

In some embodiments, in the expanded position, the loop 1044 can overliethe hook 1092 or cranialmost edge of the tubular region 1018 as in FIG.26C. In other embodiments, the loop 1044 can be positioned cranial ofthe cranialmost edge and in other embodiments the loop 1044 can bepositioned caudally of the cranialmost edge of the tubular region 1018.If the loop 1044 is sufficiently angled, a portion can overlie thecranialmost edge and another portion can be cranial or caudal of thecranialmost edge, depending on the angle of the loop.

Additionally, it is also contemplated that instead of the retrieval hookpositioned at the cranial end of the tubular region 1018, retrievalstructure can be positioned at the cranial end of the wire 1042 as inthe embodiment of FIG. 27A discussed below. The retrieval structure canin some embodiments be in the form of a hook (as in FIG. 27A) or a ball(as in FIG. 26E discussed below) and the cranial edge of the tubularregion can terminate in a ball (as in FIG. 27A).

In the expanded configuration, the transverse dimension, i.e., thediameter, of the loop 1044 is preferably less than the transversedimension of the filter 1010 at the region of the vessel engaging hooks1072 a, 1072 b. In some embodiments, the transverse dimension of theloop 1044 can be between about 10 mm to about 25 mm, although otherdimensions are also contemplated. In one embodiment, the loop 1044 wouldexpand to a diameter of about 12 mm, compared to the filter 1010 whichhas an expansion at its largest transverse dimension of about 40 mm,although it would not expand to that extent when typically used invessels with diameters less than 40 mm, and typically used in vessels nogreater than about 32 mm.

In the collapsed position of FIG. 26A, the spacer 1040 is in a collapsedreduced profile position, extending substantially linear (substantiallyparallel to a longitudinal axis of the filter) beyond the cranial end ofthe filter 1010 to facilitate delivery through the delivery sheath(catheter). When exposed from the delivery sheath (no longer within theconfines of the sheath wall), the wire 1042 returns to its looped shapememory position of FIG. 26B.

The spacer 1040, as with the other spacers disclosed herein, helps tokeep the retrieval hook away from the vessel wall to limit tissueingrowth and thereby facilitate removal.

In an alternate embodiment, instead of or in addition to the retrievalhook 1092, a ball or groove can be provided on the spacer 1040 and thespacer 1040 thereby is engageable by the retrieval snare (not shown) forretrieval of the filer 1010. This is shown in the embodiment of FIG. 26Ewherein tip 1044 a is in the form of a ball. In all other respects, thefilter is the same as in FIGS. 26A-26D and therefore has been labeledwith like reference numerals.

FIGS. 27A and 27B illustrate an alternate embodiment of the filter ofthe present invention. Filter 1110 is identical to filter 1010 exceptfor the spacer, designated generally by reference numeral 1140, theretrieval hook 1160 and the filter tubular portion 1118. Therefore,filter 1110, like filter 1010, has struts 1114 extending radially fromtubular region 1118, connecting struts 1114 a and 1114 b, joiningregions 1114 d and elongated struts 1114 c terminating in vesselengaging hooks 1072 a, 1072 b (either of the same or different size asdescribed above). For brevity, further details of the struts and hooksare not described herein since they are the same as filter 1010 and likeparts are labeled in the “1100” series instead of the “1000” series.

Spacer 1140, in the form of a wire, preferably around, extends craniallyfrom the tubular portion 1118 of filter 1140. Spacer 1140 can beattached by welding at attachment 1141, although other methods ofattachment are also contemplated. The spacer 1140 can also alternativelybe attached to an inner wall of the tubular portion 1118. The spacer1140 terminates in retrieval hook 1160. Retrieval hook 1160 includes ahooked region to receive a snare for removal. The retrieval hook 1160can in some embodiments be identical to hook 1092, although other hookshapes are also contemplated.

For delivery, the spacer 1140 is retained within the delivery sheath ina substantially straightened (substantially linear) position (FIG. 27A)extending cranially beyond the cranial end of the tubular portion 1118and substantially parallel to a longitudinal axis of the filter 1140.When exposed from the delivery sheath, it assumes a non-linear, spiralshape as shown in FIG. 27B forming a loop 1143. Note the transversedimension of spacer 1140 is less than the transverse dimension of thefilter 1140 at the mounting region at the vessel engaging hooks 1172 a,1172 b. This spacer 1140, as with the other spacers disclosed herein,helps to keep the cranial end of the filter and the retrieval hook awayfrom the vessel wall to limit tissue ingrowth and thereby facilitateremoval.

FIGS. 28A-28D illustrate an alternate embodiment of a filter spacer.Filter 1210 is identical to filter 1010 except for the spacer,designated generally by reference numeral 1240. Therefore, filter 1210,like filter 1010, has struts 1214 extending radially from tubular region1218, connecting struts 1214 a and 1214 b, joining regions 1214 d andelongated struts 1214 c terminating in vessel engaging hooks 1272 a,1272 b (either of the same or different size as described above). Forbrevity, further details of the struts and hooks are not describedherein since they are the same as filter 1010 and like parts are labeledin the “1200” series instead of the “1000” series. Retrieval hook 1292is identical to retrieval hook 1092 of FIG. 26D.

Spacer 1240 extends cranially from the tubular portion 1218 of filter1240. Filter spacer 1240 is formed from a cut hypotube 1251, preferablyby laser cutting, although other techniques are contemplated, to form aseries of struts or arms 1252. Six struts 1252 are shown, although adifferent number is contemplated. Only some of the struts 1252 arelabeled for clarity. Hypotube 1251 is attached to an internal surface oftubular portion 1218 by an interference fit, adhesive, laser welding,crimping, or other methods. The hypotube 1251 has a cranial end 1259 andan opposing caudal end. As shown, the hypotube cranial end 1259terminates caudally of the retrieval hook 1292 so as not to interferewith grasping of the hook 1292 for retrieval.

In the collapsed (non-expanded) position (condition), the caudal end ofthe hypotube 1251 extends into the region of filter 1210 underlying thestruts 1214. More specifically, as shown in FIG. 28C, in the collapsedposition, the struts 1252 of hypotube 1251 are elongated and extendsubstantially parallel to a longitudinal axis of the hypotube 1251 andtubular portion 1218 of the filter 1210. The struts 1252 extend asufficient length so their caudal ends 1260 terminate under the regionof the filter which has slots to form the struts 1214 of the filter1210. That is, the slots 1215 of the filter 1210 form the struts 1214which when expanded create the geometric regions 1250 (FIG. 28B). Whenthe filter 1210 moves from the collapsed position to the shape memoryexpanded position of FIG. 28B, the struts 1252 of hypotube 1251 move totheir expanded shape memory position, with the struts 1252 extendingthrough the geometric regions 1250 formed by struts 1214. In thisexpanded position, struts 1252 extend caudally toward the filter portion1220 within the tubular portion 1218, then emerge from the tubularportion 1218 between geometric regions 1250 and curve to extend in anopposite direction, toward the cranial end of the filter 1210, i.e.,toward the retrieval hook 1292. Note each strut 1251 extends through oneof the closed geometric spaces 1250 between the struts 1214. The struts1252, as they extend cranially, can be substantially parallel to thelongitudinal axis of tubular portion 1218 or at other angles to thelongitudinal axis of the tubular portion 1218.

In a preferred embodiment, the cranial ends 1260 of the struts 1252 ofspacer 1240 (which in the expanded position point cranially) do notextend beyond the cranialmost edge 1292 a of the retrieval hook 1292. Inthis manner, the overall length of the filter 1210 in the expandedposition is not affected by the provision of the spacer 1240.Alternatively, it is contemplated that the struts of spacer 1240 canextend beyond the cranialmost edge 1292 a. Note also, the spacer 1240does not increase the overall diameter of the filter 1210 in thecollapsed configuration since the struts 1252 are positioned within thetubular portion 1218 and between the collapsed struts 1214 in thedelivery position. The multiple struts 1252 also provide multiple armsto form a spacer of additional strength if desired as compared to aspacer having a single strut.

In the embodiment of FIGS. 28A-28C, the cranial end 1259 of the hypotube1251 terminates cranially of the tubular portion 1218 so it is exposedas shown. In an alternate embodiment of FIG. 28E, the cranial end 1259′of hypotube 1251′ terminates flush or caudally spaced from the cranialedge of the tubular portion 1218 so it is not exposed. In all otherrespects, hypotube 1251′ (with struts 1252′ terminating in caudal end1260′) is identical to hypotube 1251 of FIG. 28 a.

FIGS. 28A-28C illustrate the struts formed from a hypotube. In analternate embodiment, instead of forming the spacer 1240 from ahypotube, the spacer can be formed of a series of wires. In thisembodiment, the wires, preferably six, although a different number couldbe provided, are attached at their cranial ends to an internal surfaceof tubular portion 1218 of filter 1210. The wires, like struts 1252,extend caudally toward the filter portion 1220 within the tubularportion 1218, then emerge from the tubular portion 1218 through thegeometric regions formed by the filter struts and curve to extend in anopposite direction, toward the cranial end of the filter 1210, i.e.,toward the retrieval hook 1290. Each wire, like struts 1252, extendsthrough one of the closed geometric spaces 1250 between the struts 1214.In the preferred embodiment, the tips of the wires do not extend beyondthe cranialmost edge 1292 a of the retrieval hook 1292. In this manner,the overall length of the filter 1210 in the expanded position is notaffected by the provision of the wire spacer. Note also, the wire spacerdoes not increase the overall diameter of the filter 1210 in thecollapsed configuration since the wires are positioned within thetubular portion 1218 and between the collapsed struts 1214 in thedelivery position. The multiple wires also provide multiple arms to forma spacer of additional strength as compared to a spacer having a singlewire.

Although the cranial tips of the wires in a preferred embodiment do notextend beyond the cranial edge of the filter 1210, it is contemplatedthat in alternate embodiments the wires can extend cranially beyond thecranialmost edge.

FIGS. 29A-29D illustrate several alternate embodiments of the filter ofthe present invention wherein the spacer includes a tip placed on theouter diameter of the filter.

Turning first to the embodiment of FIGS. 29A and 29B, filter 1310 isidentical to filter 1010 except for the spacer, designated generally byreference numeral 1340, and the filter retrieval structure. Therefore,filter 1310, like filter 1010, has struts 1314 extending radially fromtubular region 1318, connecting struts 1314 a and 1314 b, joiningregions 1314 d and elongated struts 1314 c terminating in vesselengaging hooks 1372 a, 1372 b (either of the same or different size asdescribed above). For brevity, further details of the struts and hooksare not described herein since they are the same as filter 1010 and likeparts are labeled in the “1300” series.

In this embodiment, a hypotube 1341 forming the spacer 1340 is attachedto a cranial end of the filter 1310. The hypotube spacer 1341 has acranial end and an opposing caudal end. The hypotube 1341 is preferablymade of shape memory material such as Nitinol, although other materialsare also contemplated. The hypotube 1341 is attached to the outersurface of the filter 1310 at the cranial end, preferably over the outersurface of the tubular region 1318. The collapsed position of the filter1310 with the spacer 1340 attached thereto is shown in FIG. 29A. Thehypotube 1341 can be attached to the tubular portion by an interferencefit, adhesive, laser welding, crimping, or other methods. The hypotube1341 is cut, preferably by laser cutting, although are methods arecontemplated to form a series of struts 1344. In the collapsed position,the struts 1344 preferably extend substantially parallel to alongitudinal axis of the filter, overlying the tubular portion 1318 anda portion of the filter struts 1314.

In the expanded position of FIG. 29B, the struts or arms 1344 of spacer1340 expand to an umbrella like shape, with tips 1346 facing toward thecaudal end of the filter 1310. That is, the arms (struts) extendcaudally, then curve radially outwardly at an angle between about 60degrees and about 100 degrees (although other angles are contemplated)and then bend at region 1347 to extend longitudinally, and in someinstances substantially parallel to a longitudinal axis of the filter1310, in a caudal direction, terminating in tips 1346. In theillustrated embodiment, the tips 1346 terminate caudally of the filterportion of the filter 1310, spaced radially from the tubular region1318, although in other embodiments the tips 1346 can terminate furthercaudally.

A groove 1348 and enlarged head 1345 are formed at the cranial end ofthe hypotube 1341 configured to retrieve a retrieval snare (not shown)for removal of the filter 1310. Instead of the groove/enlarged headstructure, a hook can be formed on the cranial end of the hypotube forretrieval. This is shown in the embodiment of FIG. 29C which filter 1310is identical to the embodiment of FIG. 29B and therefore is labeledidentically, except for retrieval hook 1349 extending from hypotube1341. Hypotube 1341′ is identical to hypotube 1341 in all other respectsand therefore has been labeled the same as hypotube 1341 except with“prime designations.” Note the retrieval hook 1349 of filter 1310 couldoptionally have the structure of hook 1292 described above, or haveother structures to facilitate grasping by a removal tool.

Note that the configuration and directional component of the arms 1344(and 1344′) can provide easier retrieval of the filter since filterretrieval is in the cranial direction and the arms can more easily slidefrom the tissue as the tips point caudally. Note by use of a separatehypotube with a spacer which is mountable over the filter, an existingfilter can be utilized and modified to include a spacer by mounting thehypotube to the cranial end.

FIG. 29D illustrates an alternate embodiment of the present inventionwherein the spacer is attached to the filter having a retrieval hook.That is, in this embodiment, instead of the hypotube having a retrievalstructure as in the embodiment of FIGS. 29A and 29C, the filter has theretrieval structure and the hypotube is placed caudally of the retrievalstructure.

More specifically, filter 1410 is identical to filter 1010 of FIG. 26Bexcept for the spacer designated generally by reference numeral 1440.Therefore, filter 1410, like filter 1010, has struts 1414 extendingradially from tubular region 1418, connecting struts 1414 a and 1414 b,joining regions 1414 d and elongated struts 1414 c terminating in vesselengaging hooks 1472 a, 1472 b (either of the same or different size asdescribed above). For brevity, further details of the struts and hooksare not described herein since they are the same as filter 1010, andlike parts are labeled in the “1400” series instead of the “1000”series. Retrieval hook 1492 is identical to retrieval hook 1092 of FIG.26D.

Spacer 1440 includes a hypotube 1441 cut, e.g., by laser cutting,although other methods are contemplated, to form a series of struts orarms 1444. Spacer 1440 and hypotube 1441 are identical to spacer 1340and hypotube 1341 of FIGS. 29B and 29C, except that it does not haveretrieval structure. Instead the filter 1410 has a retrieval hook 1492.The hypotube 1441 therefore terminates at its cranial end with acircular edge 1445. Hypotube 1441, like hypotube 1440, has arms orstruts with curved regions 1447 terminating in caudally directed tips1446. Note by use of a separate hypotube with a spacer which ismountable over the filter, an existing filter can be utilized andmodified to include a spacer by mounting the hypotube to the cranialend. Although formed form a hypotube, as in the embodiment of FIGS. 29Band 29C, the spacer 1440 can alternatively be formed from a series ofwires.

To enable movement between an expanded and collapsed configuration, thefilter of the embodiments described herein, as noted above, ispreferably made of shape memory metal material, such as Nitinol, anickel titanium alloy, and preferably manufactured from a laser cuttube. It is also contemplated that to facilitate passage of the filterthrough the lumen of the delivery sheath 700 (shown in FIG. 13 inconjunction with the method of insertion) and into the vessel, ifdesired, cold saline can be injected into the delivery sheath orcatheter 700 and around the filter in its collapsed position within thedelivery sheath 700. This shape memory material characteristicallyexhibits rigidity in the austenitic state and more flexibility in themartensitic state. The cold saline maintains the temperature dependentfilter in a relatively softer condition as it is in the martensiticstate within the sheath. This facilitates the exit of filter from thesheath 700 as frictional contact between the filter and the innersurface of the sheath would otherwise occur if the filter was maintainedin a rigid, i.e. austenitic, condition.

Once exposed from the delivery sheath or catheter 700, the filter is nolonger cooled and is exposed to the warmer body temperature, whichcauses the filter to return towards its austenitic memorized expandedconfiguration.

In the placement (expanded) configuration, the filter moves towards itsmemorized position and the extent it returns to its fully memorizedposition will be dependent on the size of the vessel in which the filteris inserted. (The larger the vessel, the closer the filter comes toreturning to its fully memorized position). The extent of movement ofthe spacer(s) to its fully memorized position could also be limited bythe size of the vessel.

FIGS. 13-15 illustrate delivery and placement of the filter 10, by wayof example, in the inferior vena cava. Delivery catheter or sheath 700is inserted through the femoral vein “f” and advanced through the iliacarteries into the inferior vena cava. Delivery catheter 700 is withdrawnonce the tip of the sheath is adjacent the structure so that withdrawalof the sheath would place the filter in the desired location of FIG. 15.Tubing 704 and valve assembly 706 enable saline injection. Deliverycatheter 700 is withdrawn to enable filter 10 to be warmed by bodytemperature to transition to the expanded placement configuration. Theother filters described herein could be inserted in the same manner.Note it is implanted in the orientation such that filter section 19 isdownstream of the flared section 17. This enables blood clots or otherparticles to be directed to the center of the filter section by theangled struts. Thus the direction of insertion, e.g. upstream ordownstream direction, will determine how the filter is to be positionedin the delivery catheter.

The foregoing filters can be removed from access through the internaljugular or femoral vein. Various methods can be used to remove thefilter such as those described in commonly assigned U.S. Pat. Nos.7,704,266 and 8,162,972 the entire contents of which are incorporatedherein by reference, including for example, slotted hooks, graspers,etc.

A recess or cutout is preferably provided at the tubular end portion toform a hook portion or grasping portion, as shown for example in FIGS. 7and 9, having a curved hook 92 at the proximalmost end to receive asnare or other device for removal as described in the filter of the '266and '972 patents.

This hook 92 is configured to receive a retrieval snare or otherretrieval device. A portion of the wall of the hook 90 is cut out toexpose the annular interior surface 94. This annular interior surface 94extends from radiused region 95 to proximalmost edge 96. The interiorsurface 94, for ease of explanation, can be considered to have aninterior surface at the radiused region 95 and an interior surface 94 bat the hook 92. The interior surface 94 b accommodates a portion of atubular snare sheath. That is, the outer wall of the snare sheath (tube)can partially fit within the cut out region. This enhances removal asthe snare pulls the filter hook into collinear arrangement with thesheath tube as described and shown in FIGS. 13H-13N of the '266 patent.The radiused region 95, spaced axially (distal) from the hook 92,includes a radiused or curved edge defined by radiused side walls 97 a,97 c and top wall 97 b. The angled side walls 97 a, 97 c form cammingsurfaces to direct the hook 90 and filter into the retrieval sheath.

When the filter is grasped by the retrieval device and pulled distallyto disengage from the vessel walls, the spacers flex inwardly. This isshown for example in FIG. 15A, wherein spacers 40 a, 40 b of filter 10flex in the direction of the arrow as the filter is pulled intoretrieval sheath 800.

It should be appreciated, that the hook can be formed in other ways toprovide an interior annular surface to function in a similar manner assurface 94, i.e. to receive the snare tube. When the filter is pulledinto the retrieval sheath it is collapsed for removal.

FIG. 9A illustrates an alternate embodiment of the hook portion 600having an elongated hook 602 curving inwardly. This provides increasedhooking area for the retrieval snare.

To facilitate removal of the filter from the vessel, cold saline can ifdesired be injected onto the implanted filter to change the temperatureof the filter to move it to a relatively softer condition to facilitatethe filter being drawn into the retrieval sheath. That is, injection ofcold saline will cause the filter to approach its martensitic state,bringing the filter to a more flexible condition. The flexible conditionfacilitates the collapse and withdrawal of the filter into the retrievalsheath by decreasing the frictional contact between the filter and theinner surface of the retrieval sheath.

A delivery system which can be used for the filter of the presentinvention which includes a filter cartridge, is shown and described inthe '266 patent.

While the above description contains many specifics, those specificsshould not be construed as limitations on the scope of the disclosure,but merely as exemplifications of preferred embodiments thereof. Forexample, the foregoing filters can be inserted in other regions of thebody. Also, the foregoing filters can be made of materials other thanshape memory material. Those skilled in the art will envision many otherpossible variations that are within the scope and spirit of thedisclosure as defined by the claims appended hereto.

What is claimed is:
 1. A vessel filter comprising a first region and asecond region, the filter movable between a collapsed position fordelivery to a vessel and an expanded position for placement within thevessel, the first region having a filter portion having a convergingregion to direct particles toward a center of the filter, the filterportion converging into a tubular portion, the tubular portion having aninternal surface, the filter terminating at a cranial end, the secondregion being flared in the expanded position to have a transversedimension increasing in a direction away from the filter portion towarda caudal end, the second region including a vessel engaging portion, thefirst region having a spacer to keep the filter more toward a center ofthe vessel upon placement of the filter within the vessel, the spacerhaving a first end and a second end, the second end fixedly attached tothe internal surface of the tubular portion, the first end extendingwithin the tubular portion and emerging cranially from the tubularportion, wherein in the collapsed position of the filter the first endextends axially in an elongated position cranially of a cranial end ofthe tubular portion and in the expanded position of the filter the firstend extends radially and helically with respect to a longitudinal axisof the filter and transitions to a substantially planar looped region.2. The vessel filter of claim 1, wherein the first region includes aplurality of spaced apart elongated struts and a plurality of connectingstruts extending at an angle from the elongated struts.
 3. The vesselfilter of claim 1, wherein the looped region extends beyond a cranialedge of the tubular portion in the expanded position of the filter. 4.The vessel filter of claim 1, wherein the looped region encircles thetubular portion of the filter in the expanded position of the filter. 5.The vessel filter of claim 1, wherein the tubular portion includes aretrieval structure for removal of the filter.
 6. The vessel filter ofclaim 1, wherein the spacer has a cranial end terminating in a retrievalstructure for removal of the filter.
 7. The vessel filter of claim 6,wherein the retrieval structure includes a hook.
 8. The vessel filter ofclaim 1, wherein the filter is formed from a laser cut tube and composedof shape memory material.
 9. The vessel filter of claim 1, wherein thelooped region has a transverse dimension which does not exceed atransverse dimension of a caudal end of the filter in the expandedconfiguration.
 10. The vessel filter of claim 1, wherein the loopedregion of the spacer approximates a circle centered on the longitudinalaxis of the filter.
 11. The vessel filter of claim 1, wherein the loopedregion of the spacer curves at least 360 degrees.